1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus with an intermediate transfer member, which can be applied to a printer, a facsimile device, a copying machine and the like.
2. Related Background Art
FIG. 2 shows a main part of an electrophotographic full-color image forming apparatus (full-color printer) with an intermediate transfer system. In FIG. 2, around a photosensitive drum (image bearing member) 1, there are disposed a first charge roller 7, a cleaner 6, an intermediate transfer drum 2, a color developing means 9 and a black developing device 8. Around the intermediate transfer drum 2, there are disposed a transfer belt 3 and a charge roller 4.
The cleaner 6 serves to remove waste toner from the photosensitive drum 1 and includes a cleaning blade 5 and a cleaner container 6a. The color developing means 9 includes a magenta developing device 9M containing magenta (M) color toner, an yellow developing device 9Y containing yellow (Y) color toner, and a cyan developing device 9C containing cyan (C) color toner. The black developing device 8 contains black (BK) color toner. In FIG. 2, the reference numeral 3a denotes a transfer roller.
A yellow color toner image, a magenta color toner image and a cyan color toner image formed on the photosensitive drum 1 (in some cases, a black toner image formed on the photosensitive drum 1) are temporarily transferred onto the intermediate transfer drum 2 in a superimposed fashion at a first transfer station between the photosensitive drum 1 and the intermediate transfer drum 2 to thereby form full-color images.
Then, the full-color images on the intermediate transfer drum 2 are collectively transferred onto a transfer material P at a second transfer station between the intermediate transfer drum 2 and the transfer belt 3. Residual toner (which has not been transferred) is adhered to a surface of the intermediate transfer drum 2 passed through the second transfer station. The residual toner is charged by the charge roller 4 and then is transferred onto the photosensitive drum 1 when the intermediate transfer drum is being passed through the first transfer station again. Ultimately, the residual toner is removed from the photosensitive drum 1 by the cleaning blade 5 of the cleaner 6 to be collected into the cleaner container 6a.
However, in the above-mentioned full-color printer when the printer is stopped, after the toner images are transferred to the intermediate transfer drum 2, for example due to sheet jam, if the transfer belt 3 is urged against the intermediate transfer drum 2 without interposition of the transfer material P, the toner is adhered to the transfer belt 3. As a result, the intermediate transfer drum 2 and the transfer material P are contaminated with toner during further printing operation to thereby output a poor image.
Further, if the residual toner is adhered to the charge roller 4, the residual toner is adhered to the intermediate transfer drum 2 again or is scattered to be adhered to the transfer material P during further printing operation to thereby output a poor image.